The present invention relates to an operator unit for opening and closing a window and, more particularly, to a counterbalanced window operator.
Operators are known for moving a window between closed and open positions, for example, a window having a stationary main frame mounted in a roof of a house or other building, especially a sloped roof, and a sash hinged to the main frame at the top of the sash for pivoting toward and away from the main frame. Such operators are typically mounted on a bottom member of the main frame and connected to a bottom member of the sash for pushing the sash away from the main frame and drawing the sash into engagement with the main frame. When the window operator is actuated to move the window in an opening direction, it must overcome a component of the weight of the window, especially when the window is mounted in a roof. In order to overcome this difficulty, counterbalancing devices employing springs have been provided to counteract the weight component of the window and, thereby, reduce the force which must be applied to the operator, either by hand or by a power unit. Counterbalanced window operators are disclosed in U.S. Pat. Nos. 5,097,629 to Guhl et al. and 2,698,173 to Rydell.